With the help of the NSA, British spy
agency GCHQ captured and stored webcam images from millions of
unsuspecting users, the vast majority of whom were not suspected of
any crimes. "Substantial quantities" of the images were sexually
explicit, according to the Guardian, which broke the story Thursday.

The program, called Optic Nerve, began
in 2008 and was still active in 2012, according to an internal GCHQ
document provided by Edward Snowden. It was designed to identify
potential terror suspects through automated facial recognition
software.

The system, eerily reminiscent of the
telescreens evoked in George Orwell's 1984, was used for experiments
in automated facial recognition, to monitor GCHQ's existing
targets, and to discover new targets of interest. Such searches could
be used to try to find terror suspects or criminals making use of
multiple, anonymous user Ids.

Rather than collecting webcam chats in
their entirety, the program saved one image every five minutes from
the users' feeds, partly to comply with human rights legislation, and
also to avoid overloading GCHQ's servers. The documents describe
these users as "unselected" – intelligence agency
parlance for bulk rather than targeted collection.

There were some measures in place to
protect Yahoo users' privacy. Bulk searches were limited to metadata
only, though images from anyone with a similar username to a suspect
were shown to analysts. It's not known how much access the NSA had to the files, though information sharing between the two agencies is common.

According to the documents, there were
no measures in place to prevent the gathering of photos and
information from U.K. And U.S. citizens.

Unlike the NSA, GCHQ is
not required by UK law to "minimize", or remove, domestic
citizens' information from its databases. However, additional legal
authorisations are required before analysts can search for the data
of individuals likely to be in the British Isles at the time of the
search.

There are no such legal safeguards for
searches on people believed to be in the US or the other allied "Five
Eyes" nations – Australia, New Zealand and Canada.

One of the documents estimated that
between 3% and 11% of the images gathered contained "undesirable
nudity." From the document:

"Unfortunately … it would appear
that a surprising number of people use webcam conversations to show
intimate parts of their body to the other person. Also, the fact that
the Yahoo software allows more than one person to view a webcam
stream without necessarily sending a reciprocal stream means that it
appears sometimes to be used for broadcasting pornography."

In a statement to the Guardian, Yahoo denied any knowledge of the program.

"We were not aware of, nor would we condone, this reported activity," said a spokeswoman. "This report, if true, represents a whole new level of violation of our users' privacy that is completely unacceptable, and we strongly call on the world's governments to reform surveillance law consistent with the principles we outlined in December.

"We are committed to preserving our users' trust and security and continue our efforts to expand encryption across all of our services."